Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$162.50	6.122%	$172.4483	$172.45	$172.45	$172.40
Purchase #2	$207.33	3.639%	$214.8747	$214.87	$214.85	$214.90
Purchase #3	$79.96	3.254%	$82.5619	$82.56	$82.55	$82.60
Purchase #4	$150.76	6.458%	$160.4961	$160.50	$160.50	$160.50
Purchase #5	$157.70	4.447%	$164.7129	$164.71	$164.70	$164.70
Purchase #6	$21.48	10.849%	$23.8104	$23.81	$23.80	$23.80
Purchase #7	$187.35	5.349%	$197.3714	$197.37	$197.35	$197.40
7 purchase totals =	$967.08		$1,016.2757	$1,016.27	$1,016.20	$1,016.30